I get it's unlikely, bit also it's not far fetched that it may happen. I've been bumped off (voluntarily or not) quite a few times in the past. This is the first time I've seen one of my long haul flights completely sold out a week before (admittedly I don't often check), so I thought I'd get prepared as this is one I wouldn't mind being bumped off of.

My guess would be, don't check in online and turn up to check-in early so as to volunteer? Anything else I could try?